The present invention generally relates to steering wheels and steering shafts, and more particularly to an apparatus and method by which the steering wheel is attached to the steering shaft.
The typical steering wheel includes a rim and spokes which extend between a hub and the rim. The hub includes a splined bore which is press fit upon complementary splines formed at the end of the steering shaft. The end of the steering shaft is also threaded. After the steering wheel is properly aligned to the steering shaft it is pushed onto the end of the shaft with the end passing through the hub. A nut is screwed upon the splined/threaded end of the steering shaft. The above mounting procedure is possible since the upper side of the hub is accessible. Thereafter an air bag module, typically comprising a housing, inflator, air bag and cover, is secured to the upper side of the hub covering the nut. Other steering wheel/steering shaft attachment methods include inserting a threaded bolt into a threaded bore in the steering shaft with a key provided in the shaft and steering wheel to achieve proper alignment.
It has been proposed to replace the conventional steering wheel with an integrated steering wheel. The integrated steering wheel comprises an armature or metal core covered by a styled molded layer which covers the wheel spokes and wheel rim and also forms an air bag module cover. The air bag and air bag inflator are integrated within the steering wheel and situated between the integrally formed cover and the hub. The integrated steering wheel may also include a conventional steering wheel and a conventional air bag module comprising an air bag, inflator and cover. The steering wheel is attached to the steering shaft before the air bag module is secured to the hub of the steering wheel. Thereafter this integrated assembly is attached to the end of the steering shaft. As can be appreciated, it is no longer possible to attach the steering wheel to the steering shaft as described above, since access to the end of the steering (which extends into and through the hub) is now precluded. Consequently, new methodologies of attaching this integrated steering wheel/air bag assembly must be defined.
Since access to the front side of the steering wheel would no longer be available any attachment device will be located on the rear (or bottom) of the hub of the steering wheel. As can also be appreciated, with this attachment device located on the bottom of the hub, the assembly of the steering wheel to the steering shaft is a "blind" operation. As such, the assembly techniques must accommodate this type of operation.
In the assembly of any mating parts, there will be rotational and linear tolerances associated with both parts. It is an object of the present invention to provide an attachment system which accounts for these various tolerances.
It is a further object of the present invention to provide a clamping or gripping type of mechanism to connect the steering wheel and steering shaft.
The present invention comprises a specially shaped steering column and a gripping mechanism located on the back of a steering wheel. The top of the steering shaft contains a rectangular shaped section with a groove located in its center (or alternatively two spaced rectangular sections can be used to defined the groove). Positioned immediately below the rectangular section(s), about the shaft, is a circumferential groove. The gripping mechanism includes a first gripping (or clamping) part which is fixed to the lower side of the steering wheel hub and a slidably mounted second gripping (or clamping) part connected to the first gripping part by a threaded bolt. As will be seen below "gripping" and clamping" are used interchangeably. Each gripping part contains a flat surface which aligns with a corresponding flat side of the rectangular section of the steering shaft as the two clamping parts are moved together. This clamping action simultaneously causes the alignment of the steering wheel to a preferred orientation relative to the steering shaft. The two opposing gripping parts also mate with the circular groove, in the steering shaft, in such a manner as to remove tolerances up and down the shaft. This interconnection axially secures the steering wheel to the steering shaft.
Accordingly, the present invention comprises: a steering wheel/steering shaft assembly comprising: a steering shaft including a shaft portion having a first end, the first end including a first means for aligning and securing a steering wheel thereto. The steering wheel includes a second means, cooperating with the first means, for providing a clamp upon the steering shaft and in cooperation with the first means for causing the self-aligning of the steering wheel to a preferred orientation relative to the steering shaft. More particularly, the steering shaft includes a v-groove and a rectangular projection at its top. The second means includes two relatively movable gripping members, one of which is attached to the bottom of the steering wheel hub, which when in a clamping configuration positions a wedge within the v-groove to positively secure the wheel to the shaft and which engages the rectangular projection to align the steering wheel to a precise orientation relative to the steering shaft and to the passenger compartment.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.